The present invention relates to data storage systems, and more particularly, this invention relates to insitue packaging for attaching diodes.
In magnetic storage systems, data is commonly read from and written onto magnetic recording media utilizing magnetic transducers. Data is written on the magnetic recording media by moving a magnetic recording transducer to a position over the media where the data is to be stored. The magnetic recording transducer then generates a magnetic field, which encodes the data into the magnetic media. Data is read from the media by similarly positioning the magnetic read transducer and then sensing the magnetic field of the magnetic media. Read and write operations may be independently synchronized with the movement of the media to ensure that the data can be read from and written to the desired location on the media.
An important and continuing goal in the data storage industry is that of increasing the density of data stored on a medium. For tape storage systems, that goal has led to increasing the track density on recording tape, and decreasing the thickness of the magnetic tape medium. However, the development of small footprint, higher performance tape drive systems has created various problems in the design of a tape head assembly for use in such systems.
In a tape drive system, magnetic tape is moved over the surface of the tape head at high speed. This movement generally entrains a film of air between the head and tape. Usually the tape head is designed to minimize the spacing between the head and the tape. The spacing between the magnetic head and the magnetic tape is crucial so that the recording gaps of the transducers, which are the source of the magnetic recording flux, are in near contact with the tape to effect efficient signal transfer, and so that the read element is in near contact with the tape to provide effective coupling of the magnetic field from the tape to the read element.
Magnetoresistive (MR) sensors, such as giant magnetoresistive (GMR), anisotropic magnetoresistive (AMR) and tunnel valve magnetoresistive (TMR) sensors, are used to read data written on magnetic media. MR sensors are used extensively in the hard disk drive (HDD) and tape drive industries. MR sensors are highly sensitive to damage by electrostatic discharge (ESD) events. One means of protecting MR sensors from ESD damage is to use diode protection. It is important to note that the best location to attach the diodes for maximum protection is as close to the sensors as possible. In tape and HDDs, typically a flexible cable is attached to the MR sensors to allow a connection to external electrical devices. The cabled sensor modules (CMODs) are then assembled into a magnetic head which includes an actuator to move the sensor over the particular data track to be read. The actuation is high frequency, and the response of the actuation is slowed down by extra mass and cable rigidity, urging the use of smaller and smaller cables. In attaching the cables, the spacing between the cable leads can vary along the length of the cable. Furthermore, the spacing of the leads on the cable may change from one product to another. Diodes are typically purchased in a package and then attached in an electronic device. Several problems with the standard packaging is the significantly added mass and volume that these packaged diodes provide to the magnetic head.
In the case of modern tape drives, the space allotted to position electronics, such as diodes, near the sensors is very limited, and conventional pre-packaged electronics will not fit. Another solution that would allow for diode attachment would be to attach a chip directly to the cable through anisotropic conductive film (ACF) bonding. A limitation of both ACF and solder-type bonding used for standard surface mount packaging is that the spacing of the tabs on the chip or package and the cable must be matched precisely. For cables with spacing on the order of about 50 microns to about 200 microns, standard packages are not available. For the ACF type bonding; a problem exists of precision alignment to avoid shorting for dimensions of these sizes. Thus, the cable lead spacing must be adjusted to match the tab spacing on the chip or package. Therefore, a method of attaching diodes to the magnetic head and systems having the diodes attached in these smaller devices that avoid the problems encountered using conventional methods would be very beneficial.